Heat resistant clear polycarbonate-polysiloxane compounds

ABSTRACT

Provided herein are polycarbonate blend compositions, methods for making polycarbonate blend compositions and articles containing the polycarbonate blend composition, wherein the polycarbonate blend composition comprises a first polycarbonate and a second polycarbonate wherein the polycarbonate blend has a glass transition temperature (Tg) between 148° C. and 155° C. as measured using a differential scanning calorimetry method; a percent (%) haze of less than 3.5% and a % transmission of greater than 80% as measured using a method of ASTM D 1003-07, and wherein the blend composition possesses 80% or greater ductility in a notched izod test at −20° C. at a thickness of 0.125 inches according to ASTM D256-10.

FIELD OF THE INVENTION

The present invention relates to the development and use of heatresistant clear polycarbonate-polysiloxane compositions and usesthereof.

BACKGROUND

Polycarbonates are synthetic thermoplastic resins that may be derivedfrom bisphenols and phosgene, or their derivatives. The desiredproperties of polycarbonates include clarity or transparency, highimpact strength and toughness, heat resistance, weather and ozoneresistance, and good ductility. They are useful for forming a widevariety of products, such as by molding, extrusion, and thermoformingprocesses. Such products include articles and components that includeauto parts, electronic appliances and cell phone components. Because oftheir broad use, particularly in electronic applications or visuallyoriented applications, such as light covers, see-through protectivecoverings, lenses, and transparent films, it is desirable to providepolycarbonates with excellent weatherability, heat resistance, impactstrength, and transparency.

Prior means of improving impact performance of polycarbonates have oftenresulted in articles of manufacture that have a significant loss of heatresistance and/or transparency. Polysiloxane polycarbonates haveprovided improved impact strength performance and improved solventresistance with substantial retention of transparency compared to PChomopolymers. However, polysiloxane polycarbonates exhibit lower heatresistance compared to other polycarbonates and thus their utility islimited in some commercial applications.

There is a need for producing blends of high transparent and heatresistant polymers without substantially compromising the desiredtransparency and impact strength properties.

SUMMARY OF THE INVENTION

The present invention is directed to a polycarbonate blend compositioncomprising (a) a first polycarbonate having a glass transitiontemperature of greater than 170° C. as measured using a differentialscanning calorimetry method, wherein the first polycarbonate is derivedfrom: one or more monomers having the structure HO-A₁-Y₁-A₂-OH whereineach of A₁ and A₂ comprise a monocyclic divalent arylene group, and Y₁is a bridging group having one or more atoms, and wherein the structureis free of halogen atoms; or

polyester monomer units having the structure

wherein D comprises one or more alkyl containing C₆-C₂₀ aromaticgroup(s), or one or more C₆-C₂₀ aromatic group(s), and T comprises aC₆-C₂₀ aromatic group; and (b) a second polycarbonate wherein the secondpolycarbonate is a polysiloxane block copolymer derived from(i) the structure

wherein R comprises a C₁-C₃₀ aliphatic, a C₁-C₃₀ aromatic group, or acombination thereof, wherein Ar comprises one or more C₆-C₃₀ aromaticgroup(s), or one or more alkyl containing C₆-C₃₀ aromatic group(s),wherein E has an average value of 20-75; or(ii) the structure

wherein R comprises a C₁-C₃₀ aliphatic, a C₁-C₃₀ aromatic group, or acombination thereof, wherein R6 comprises a C₇-C₃₀ aromatic group, or acombination of a C₇-C₃₀ aromatic group and a C₇-C₃₀ aliphatic group,wherein E has an average value of 20-75; wherein the blend compositionhas a glass transition temperature (Tg) between 148° C. and 155° C. asmeasured using a differential scanning calorimetry method; wherein theblend composition has a percent (%) haze of less than 3.5% and a %transmission of greater than 80% as measured using a method of ASTM D1003-07; wherein the blend composition possesses 80% or greaterductility in a notched izod test at −20° C. at a thickness of 0.125inches according to ASTM D 256-10.

The blend composition may have an MVR of between 6 and 12 cm³/10 minuteas measured at 300° C. at 1.2 kilograms using the method of ASTM D1238-10. The blend second polycarbonate of the blend composition mayfurther comprise a carbonate unit derived from the polysiloxane blockshaving the structure

wherein E has an average value of between 20 and 75.

The first polycarbonate comprises carbonate units derived from themonomers 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP),1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane(Bisphenol-AP), and/or1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (Bisphenol-TMC) ora combination thereof.

The first polycarbonate of the blend composition may comprise greaterthan 30 wt % of carbonate units derived from3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP),1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane(Bisphenol-AP), and/or1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (Bisphenol-TMC) ora combination thereof. The first polycarbonate of the blend compositionmay comprise a % haze of less than 1.5% as measured using the method ofASTM D 1003-07 at 0.125 inches in part thickness. The firstpolycarbonate of the blend composition may further comprise2,2-bis(4-hydroxyphenyl)propane (Bisphenol-A). The first polycarbonateof the blend composition may further comprise aromatic ester unitsderived from isophthalic acid or terephthalic acids or isophthalic acidesters or terephthalic esters or a combination isophthalic acid orterephthalic acids or isopthalic acid esters or terephthalic acidesters. The first polycarbonate of the blend composition may furthercomprise carbonate units or ester units derived from Bisphenol-A.

The second polycarbonate of the blend composition may have a haze ofless than 3% as measured using the method of ASTM D 1003-07 at 0.125inches in part thickness and having 100% ductility at −20° C. asmeasured using the method of ASTM D 256-10 at 0.125 inches in partthickness. The first and second polycarbonates of the blend compositionmay be made from either an interfacial polymerization process or a meltpolymerization process. The blend composition may contain a wt %siloxane in the second polycarbonate that is between 5 wt % and 7 wt %based on the total weight of the second polycarbonate. The blendcomposition may contain a wt % of the siloxane in the blend compositionthat is between 4 wt % and 6 wt % based on the total weight of thepolycarbonate blend composition.

The second polycarbonate of the blend composition may comprise greaterthan 75 wt % of the polycarbonate blend composition and wherein thefirst polycarbonate comprises less than 25 wt % of the polycarbonateblend composition based on the sum of the first and secondpolycarbonates being equal to 100 wt %. The first polycarbonate of theblend composition may comprise4,4′-(3,3,5-trimethylcyclohexane-1,1-diyl)diphenol.

The present invention is also directed to a polycarbonate blendcomposition comprising: a first polycarbonate, which is acopolycarbonate having a glass transition temperature of 170° C. orgreater as measured using differential scanning calorimetry and derivedfrom a combination of bisphenol-A and a second monomer that is free ofhalogens and having the structure

HO-A₁-Y₁-A₂-OH

wherein each of A₁ and A₂ comprises a monocyclic divalent arylene group,and Y₁ comprises at least one of the following: —O—, —S(O)—, —S(O)2-,methylene, cyclohexyl-methylene, 2-[2.2.1]-bicycloheptylidene,ethylidene, isopropylidene, neopentylidene, cyclohexylidene,cyclopentadecylidene, cyclododecylidene, and adamantylidene, wherein A₁,A₂ and Y₁ are free of halogen atoms; and a second polycarbonate, whichis a polysiloxane block copolycarbonate derived from at leastbisphenol-A and

wherein the average value of E is between 30 and 50, or

wherein the average value of E is between 30 and 50, wherein thesiloxane content in the polysiloxane block co-polycarbonate is between 2wt % and 10 wt % siloxane based on the total weight of the polysiloxaneblock co-polycarbonate; wherein the polycarbonate blend compositioncomprises between 10% and 20% of the first polycarbonate and between 90wt % and 80 wt % of a second polycarbonate based on the sum of the firstand the second polycarbonate being equal to 100 wt %; wherein thepolycarbonate blend composition has a glass transition temperature (Tg)of between 148° C. and 155° C. as measured using a differential scanningcalorimetry method; wherein the polycarbonate blend composition has a %haze of less than 3% and a % transmission of greater than 80% asmeasured using the method of ASTM D 1003-07; and, wherein thepolycarbonate blend composition possesses at least 75% ductility in anotched izod test at −20° C. at a thickness of 0.125 inches according toASTM D 256-10. The first polycarbonate is derived from at leastBisphenol-A and one or more of the monomers,3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP), Bisphenol-AP,Bisphenol-TMC or a combination of isophthalic and phthalic acids or acombination of isophthalic and phthalic acid esters. The blendcomposition may further comprise at least one of the followingadditives: mold release agents, thermal stabilizers, UV stabilizers, orcolorants.

The present invention is also directed to a polycarbonate blendcomposition comprising: a first polycarbonate comprising carbonate unitsderived from bisphenol-A and3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP), wherein thefirst polycarbonate has a mole % of carbonate units derived from PPPBPbetween 30-35 mole % and a mole % carbonate units derived fromBisphenol-A between 65 and 70 mole %, a second polycarbonate comprisingcarbonate units derived from Bisphenol-A and carbonate units derivedfrom

wherein, E has an average value of between 40 and 50 and wherein the wt% siloxane in the second polycarbonate is between 5 wt % and 7 wt %based on the weight of the second polycarbonate being 100%; wherein, thefirst polycarbonate comprises between 10-20 wt % and the secondpolycarbonate comprises between 80-90 wt % based on the wt % of thefirst and the second polycarbonate being 100%; wherein the polycarbonateblend composition comprises between 10% and 20% of the firstpolycarbonate and between 80 wt % and 90 wt % of the secondpolycarbonate based on the sum of the first and the second polycarbonatebeing equal to 100 wt %; wherein, the polycarbonate blend compositionhas a glass transition temperature (Tg) of between 148° C. and 155° C.as measured using a differential scanning calorimetry method; wherein, amolded article of the polycarbonate blend composition has a % haze ofless than 3% and a % transmission of greater than 80% as measured usingthe method of ASTM D 1003-07 at 0.125 inches in part thickness; whereinthe polycarbonate blend composition possesses at least 75% ductility ina notched izod test at −20° C. at a thickness of 0.125 inches accordingto ASTM D 256-10.

The present invention is also directed to a method for making apolycarbonate blend composition comprising the steps of (a) selecting afirst polycarbonate; (b) selecting a second polycarbonate; and (c)blending the first polycarbonate with the second polycarbonate to form acomposition having a glass transition temperature (Tg) of between 145°C. and 155° C. as measured using a differential scanning calorimetrymethod, a % haze of less than 3.5% and a % transmission of greater thanas measured using the method of ASTM D 1003-07; and, possesses 80% orgreater ductility in a notched izod test at −20° C. at a thickness of0.125 inches according to ASTM D 256-10. The first polycarbonatecomprises carbonate units derived from at least Bisphenol-A and one ormore of the following monomers PPPBP; Bisphenol-A; Bisphenol-TCM; acombination of isophthalic and phthalic acids; and a combination ofisophthalic and phthalic acid esters. The second polycarbonate comprisescarbonate units derived from Bisphenol-A and

wherein the average value of E is between 30 and 50, or

wherein the average value of E is between 30 and 50. Step (c) of themethod may comprise extrusion.

The present invention is also directed to an article molded from apolycarbonate blend composition described above. The article can be acomponent of a cell phone cover or computer housing, wherein the articlemay be molded from the polycarbonate blend composition(s) encompassed bythis disclosure.

DETAILED DESCRIPTION

The present invention is directed to a polycarbonate blend compositionhaving a combination of a high heat polycarbonate (as described in thisdisclosure) and a polycarbonate polysiloxane copolymer (as described inthis disclosure).

1. Definitions

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thespecification and the appended claims, the singular forms “a,” “and” and“the” include plural references unless the context clearly dictatesotherwise.

“Alkyl” as used herein may mean a linear, branched, or cyclic group,such as a methyl group, ethyl group, n-propyl group, isopropyl group,n-butyl group, isobutyl group, tert-butyl group, n-pentyl group,isopentyl group, n-hexyl group, isohexyl group, cyclopentyl group,cyclohexyl group, and the like.

“Copolymer” as used herein may mean a polymer derived from two or morestructural unit or monomeric species, as opposed to a homopolymer, whichis derived from only one structural unit or monomer.

“C₃-C₆ cycloalkyl” as used herein may mean cyclopropyl, cyclobutyl,cyclopentyl and cyclohexyl.

“Glass Transition Temperature” or “Tg” as used herein may mean themaximum temperature that a polycarbonate will have one or more usefulproperties. These properties include impact resistance, stiffness,strength, and shape retention. The Tg of a polycarbonate therefore maybe an indicator of its useful upper temperature limit, particularly inplastics applications. The Tg may be measured using a differentialscanning calorimetry method and expressed in degrees Celsius.

The glass transition temperature of a polycarbonate may depend primarilyon the composition of the polycarbonate. Polycarbonates that are formedfrom monomers having more rigid and less flexible chemical structuresthan Bisphenol-A generally have higher glass transition temperaturesthan Bisphenol-A, while polycarbonate that are formed from monomershaving less rigid and more flexible chemical structures thanBisphenol-A, for example, generally have lower glass transitiontemperatures than Bisphenol-A. For example, a polycarbonate describedherein formed from 33 mole % of a rigid monomer,3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (“PPPBP”), and 67 mole% Bisphenol-A has a glass transition temperature of 198° C., while apolycarbonate described herein formed from Bisphenol-A, but also having6 wt % of siloxane units, a flexible monomer, has a glass transitiontemperature of 145° C.

Mixing of two or more polycarbonates having different glass transitiontemperatures may result in a glass transition temperature value for themixture that is intermediate between the glass transition temperaturesof the polycarbonates that are mixed.

The glass transition temperature of a polycarbonate may also be anindicator of the molding or extrusion temperatures required to formpolycarbonate parts. The higher the glass transition temperature of thepolycarbonate the higher the molding or extrusion temperatures that areneeded to form polycarbonate parts.

The glass transition temperatures (Tg) described herein are measures ofheat resistance of the corresponding polycarbonate and polycarbonateblends. The Tg can be determined by differential scanning calorimetry.The calorimetry method may use a TA Instruments Q1000 instrument, forexample, with setting of 20° C./min ramp rate and 40° C. starttemperature and 200° C. end temperature

“Halo” as used herein may be a substituent to which the prefix isattached is substituted with one or more independently selected halogenradicals. For example, “C₁-C₆ haloalkyl” means a C₁-C₆ alkyl substituentwherein one or more hydrogen atoms are replaced with independentlyselected halogen radicals. Non-limiting examples of C₁-C₆ haloalkylinclude chloromethyl, 1-bromoethyl, fluoromethyl, difluoromethyl,trifluoromethyl, and 1,1,1-trifluoroethyl. It should be recognized thatif a substituent is substituted by more than one halogen radical, thosehalogen radicals may be identical or different (unless otherwisestated).

“Halogen” or “halogen atom” as used herein may mean a fluorine,chlorine, bromine or iodine atom.

“Haze” as used herein may mean that percentage of transmitted light,which in passing through a specimen deviates from the incident beam byforward scattering. Percent (%) haze may be measured according to ASTM D1003-07.

“Heteroaryl” as used herein may mean any aromatic heterocyclic ringwhich may comprise an optionally benzocondensed 5 or 6 memberedheterocycle with from 1 to 3 heteroatoms selected among N, O or S, Nonlimiting examples of heteroaryl groups may include pyridyl, pyrazinyl,pyrimidinyl, pyridazinyl, indolyl, imidazolyl, thiazolyl, isothiazolyl,pyrrolyl, phenyl-pyrrolyl, furyl, phenyl-furyl, oxazolyl, isoxazotyl,pyrazolyl, thienyl, benzothienyl, isoindolinyl, benzoimidazolyl,quinolinyl, isoquinolinyl, 1,2,3-triazolyl, 1-phenyl-1,2,3-triazolyl,and the like.

“Hindered phenol stabilizer” as used herein may mean3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid, octadecyl ester.

“Melt Volume Rate” (MVR) as used herein may mean the flow rate of apolymer in a melt phase as determined using the method of ASTM 1238-10.The MVR of a molten polymer is measured by determining the amount ofpolymer that flows through a capillary of a specific temperature over aspecified time using standard weights at a fixed temperature. MVR isexpressed in cubic centimeter per 10 minutes. The higher the MVR valueof a polymer at a specific temperature, the greater the flow of thatpolymer at that specific temperature.

“Percent transmission” or “% transmission” as used herein may mean theratio of transmitted light to incident light and may be measuredaccording to ASTM D 1003-07.

“PETS release agent” as used herein may mean pentaerythritoltetrastearate, mold release.

“Phosphite stabilizer” as used herein may meantris-(2,4-di-tert-butylphenyl) phosphite.

“Polycarbonate” as used herein may mean an oligomer or polymercomprising residues of one or more polymer structural units, ormonomers, joined by carbonate linkages.

“Straight or branched C₁-C₃ alkyl” or “straight or branced C₁-C₃ alkoxy”as used herein may mean methyl, ethyl, n-propyl, isopropyl, methoxy,ethoxy, n-propoxy and isopropoxy.

Unless otherwise indicated, each of the foregoing groups may beunsubstituted or substituted, provided that the substitution does notsignificantly adversely affect synthesis, stability, or use of thecompound.

The terms “structural unit” and “monomer” are interchangeable as usedherein.

For the recitation of numeric ranges herein, each intervening numberthere between with the same degree of precision is explicitlycontemplated. For example, for the range of 6-9, the numbers 7 and 8 arecontemplated in addition to 6 and 9, and for the range 6.0-7.0, thenumber 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 areexplicitly contemplated.

2. Polycarbonate Blend Composition

The herein described polycarbonate blend composition comprises a firstpolycarbonate and a second polycarbonate. The polycarbonate blendcomposition provides improved impact strength performance and improvedsolvent resistance while substantially retaining transparency typical ofpolycarbonate homopolymers. The polycarbonate blend composition furtherprovides heat resistance characteristics similar to those of BPApolycarbonate homopolymers.

The polycarbonate blend may comprise greater than 50 wt %, 60 wt %, 65wt %, 70 wt %, 75 wt %, 80 wt %, 85 wt %, 90 wt %, or 95 wt % of thesecond polycarbonate. The polycarbonate may comprise between 80 wt % and90 wt % of the second polycarbonate. The polycarbonate blend maycomprise less than 50 wt %, 40 wt %, 35 wt %, 30 wt %, 25 wt %, 20 wt %,15 wt %, 10 wt %, or 5 wt % of the first polycarbonate. Thepolycarbonate blend may comprise between 10 wt % and 20 wt % of thefirst polycarbonate. The sum of the weight (wt) percentages for thefirst and second polycarbonates may equal 100 wt %. The first and/orsecond polycarbonate may be branched.

The polycarbonate blend composition may have a glass transitiontemperature (Tg) of between 140° C. and 160° C., between 145° C. and155° C., between 148° C. and 151° C., or between 148° C. and 155° C. asmeasured using differential scanning calorimetry.

The polycarbonate blend composition may have a percent (%) haze of lessthan 5%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0% or 1.0% using the method ofASTM D 1003-07 on parts 0.125 inches in thickness. The polycarbonateblend composition may have a transmission of greater than 65%, 70%, 75%,80%, 85%, 90%, or 95% as measured using the method of ASTM D 1003-07 onparts 0.125 inches in thickness. The polycarbonate blend composition mayhave a percent haze of less than of 3.5% and a percent transmission ofgreater than 80% as measured using a method of ASTM D 1003-07 on parts0.125 inches in thickness. The polycarbonate blend composition may havea percent haze of less than of 3.0% and a percent transmission ofgreater than 80% as measured using a method of ASTM D 1003-07 on parts0.125 inches in thickness.

The polycarbonate blend composition may possess 60%, 65%, 70%, 75%, 80%,85%, 90%, 95% or greater ductility in a notched izod test at −10° C.,−15° C., −20° C., −25° C., −30° C., or −35° C. at a thickness of 0.125inches according to ASTM D 256-10. The polycarbonate blend compositionmay possess 100% ductility in a notched izod test at −10° C., −15° C.,−20° C., −25° C., −30° C., or −35° C. at a thickness of 0.125 inchesaccording to ASTM D 256-10. Notched Izod measurements, in accordancewith ASTM D 256-10, may be conducted on test bars that measure 0.125 inthickness by 0.5 in wide and 2.5 long at room temperature (23° C.) andlower temperatures as indicated in the tables provided in the Examplesbelow. The polycarbonate blend composition may possess an 80% or greaterductility in a notched izod test at −20° C. at a thickness of 0.125inches according to ASTM D 256-10. For example, if the blend compositionexhibits 100% ductility, then if 5 samples are tested in a notched izodprotocol, all 5 samples exhibit ductile breaks. A sample may mean apolycarbonate test bar. The test bar may have a defined thickness. Thepolycarbonate test bar has undergone ductile failure in a notched izodtest if, after impact, the bar remains as a single piece, with the twoends of the bar attached and rigid (i.e. self supporting). A test barhas undergone brittle failure if after impact either the two ends of thebar have broken into two separate pieces or if they are attached by onlya thin, flexible connection of plastic.

MVR measures the rate of extrusion of a thermoplastic through an orificeat a prescribed temperature and load. MVR may be measured in accordingto the method ASTM D 1238-10 at 1.2 kilogram at 300° C. The hereindescribed polycarbonate blend compositions may have an MVR of 4 to 12cubic centimeters, of 5 to 11 cubic centimeters, of 6 to 10 cubiccentimeters, of 7 to 9 cubic centimeters, 6 to 12 cubic centimeters, 8to 12 cubic centimeters, or 6.5 to 10.5 cubic centimeters per 10 minutes(cc/10 min). In a specific embodiment, a suitable polycarbonatecomposition has an MVR measured at 300° C./1.2 kg according to ASTM D1238-10, of 0.5 to 50 cc/10 min, specifically 1 to 25 cc/10 min, andmore specifically 3 to 20 cc/10 min. Mixtures of polycarbonates ofdifferent flow properties may be used to achieve the overall desiredflow property.

The polycarbonate blend composition may exhibit heat resistance similarto a bisphenol A polycarbonate homopolymer. The polycarbonate blendcomposition exhibits a heat resistance that is higher than the secondpolycarbonate in the blend as described below. The polycarbonate blendcomposition exhibits heat resistance lower than the levels achieved withthe first polycarbonate as described below.

a. First Polycarbonate—

Described herein is the first polycarbonate of the polycarbonate blendcomposition. The first polycarbonate may be a homopolycarbonate or acopolycarbonate derived from one dihydroxy monomer or a combination oftwo or more dihydroxy aromatic monomers, respectively, such that theglass transition temperature of the homopolycarbonate or thecopolycarbonate has a Tg of at least 170° C. The dihydroxy aromaticmonomer of the homopolycarbonate must produce a polycarbonate with a Tgof >170° C. If more than one dihydroxy aromatic monomers are present inthe copolycarbonate, the combination of dihydroxy aromatic monomers mustproduce a polycarbonate with a Tg of >170° C.

The first polycarbonate may alternatively be a polyester polycarbonatecopolymer having a Tg of at least 170° C. The polyester polycarbonatemay be a combination of a polyester structural unit and a polycarbonatestructural unit. The polyester structural unit may be derived from aC₆-C₂₀ aromatic dicarboxylic acid and one or more dihydroxy aromaticmonomers. The polycarbonate structural unit may be derived from one ormore dihydroxy aromatic monomers. The dihydroxy aromatic monomers of thepolyester structural unit and the polycarbonate structural unit may bethe same or different. Details of these structural units of the firstpolycarbonate are discussed below.

(1) Homopolycarbonate/Copolycarbonate

The first polycarbonate may be a homopolycarbonate or a copolycarbonate.The term “polycarbonate” and “polycarbonate resin” mean compositionshaving repeating structural carbonate units of the formula (1):

in which at least about 60% of the total number of R¹ groups arearomatic organic groups and the balance thereof are aliphatic,alicyclic, or aromatic groups. In one embodiment, each R¹ is an aromaticorganic group, for example a group of the formula (2):

-A¹-Y¹-A²-  (2)

wherein each of A¹ and A² is a monocyclic divalent aryl group and Y¹ isa bridging group having one or two atoms that separate A¹ from A². Forexample, one atom may separate A¹ from A², with illustrative examples ofthese groups including —O—, —S—, —S(O)—, —S(O)₂—, —C(O)—, methylene,cyclohexyl-methylene, 242.2.11-bicycloheptylidene, ethylidene,isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene,cyclododecylidene, and adamantylidene. The bridging group Y¹ may be ahydrocarbon group or a saturated hydrocarbon group such as methylene,cyclohexylidene, or isopropylidene.

The polycarbonates may be produced from dihydroxy compounds having theformula HO—R¹—OH, wherein R¹ is defined as above for formula (1). Theformula HO—R¹—OH includes bisphenol compounds of formula (3):

HO-A¹-Y¹-A²-OH  (3)

wherein Y¹, A¹ and A² are as described above. Included are bisphenolcompounds of general formula (4):

wherein R^(a) and R^(b) each represent a halogen atom or a monovalenthydrocarbon group and may be the same or different; p and q are eachindependently integers of 0 to 4; and X^(a) represents one of the groupsof formula (5):

wherein R^(c) and R^(d) each independently represent a hydrogen atom ora monovalent linear alkyl or cyclic alkylene group and R^(e) is adivalent hydrocarbon group. In an embodiment, R^(c) and R^(d) representa cyclic alkylene group; or a heteroatom-containing cyclic alkylenegroup comprising carbon atoms and heteroatoms with a valency of two orgreater. In an embodiment, a heteroatom-containing cyclic alkylene groupcomprises at least one heteroatom with a valency of 2 or greater, and atleast two carbon atoms. Suitable heteroatoms for use in theheteroatom-containing cyclic alkylene group include —O—, —S, and —N(Z)—,where Z is a substituent group selected from hydrogen, C₁₋₁₂ alkyl,C₁₋₁₂ alkoxy, or C₁₋₁₂ acyl. Where present, the cyclic alkylene group orheteroatom-containing cyclic alkylene group may have 3 to 20 atoms, andmay be a single saturated or unsaturated ring, or fused polycyclic ringsystem wherein the fused rings are saturated, unsaturated, or aromatic.

Other bisphenols containing substituted or unsubstituted cyclohexaneunits may be used, for example, bisphenol of formula (6):

wherein each R^(f) is independently hydrogen, C₁₋₁₂ alkyl, or halogen;and each R^(g) is independently hydrogen or C₁₋₁₂ alkyl. Thesubstituents may be aliphatic or aromatic, straight-chain, cyclic,bicyclic, branched, saturated, or unsaturated. Suchcyclohexane-containing bisphenols, for example the reaction product oftwo moles of a phenol with one mole of a hydrogenated isophorone, areuseful for making polycarbonate polymers with high glass transitiontemperatures and high heat distortion temperatures.

Other useful dihydroxy compounds having the formula HO—R¹—OH includearomatic dihydroxy compounds of formula (7):

wherein each R^(h) is independently a halogen atom, a C₁₋₁₀ hydrocarbylsuch as a C₁₋₁₀ alkyl group, a halogen substituted C₁₋₁₀ hydrocarbylsuch as a halogen-substituted C₁₋₁₀ alkyl group, and n is 0 to 4. Thehalogen is usually bromine.

Some exemplary dihydroxy compounds include: 4,4′-dihydroxybiphenyl,1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene,bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)diphenylmethane,bis(4-hydroxyphenyl)-1-naphthylmethane, 1,2-bis(4-hydroxyphenyl)ethane,1,1-bis(4-hydroxyphenyl)-1-phenylethane,2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane,bis(4-hydroxyphenyl)phenylmethane,2,2-bis(4-hydroxy-3-bromophenyl)propane,1,1-bis(hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxyphenyl)isobutene,1,1-bis(4-hydroxyphenyl)cyclododecane,trans-2,3-bis(4-hydroxyphenyl)-2-butene,2,2-bis(4-hydroxyphenyl)adamantine, alpha,alpha′-bis(4-hydroxyphenyl)toluene, bis(4-hydroxyphenyl)acetonitrile,2,2-bis(3-methyl-4-hydroxyphenyl)propane,2,2-bis(3-ethyl-4-hydroxyphenyl)propane,2,2-bis(3-n-propyl-4-hydroxyphenyl)propane,2,2-bis(3-isopropyl-4-hydroxyphenyl)propane,2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane,2,2-bis(3-t-butyl-4-hydroxyphenyl)propane,2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,2,2-bis(3-allyl-4-hydroxyphenyl)propane,2,2-bis(3-methoxy-4-hydroxyphenyl)propane,2,2-bis(4-hydroxyphenyl)hexafluoropropane,1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene,1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene,4,4′-dihydroxybenzophenone, 3,3-bis(4-hydroxyphenyl)-2-butanone,1,6-bis(4-hydroxyphenyl)-1,6-hexanedione, ethylene glycolbis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ether,bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide,bis(4-hydroxyphenyl)sulfone, 9,9-bis(4-hydroxyphenyl)fluorine,2,7-dihydroxypyrene,6,6′-dihydroxy-3,3,3′,3′-tetramethylspiro(bis)indane (“spirobiindanebisphenol”), 3,3-bis(4-hydroxyphenyl)phthalide,2,6-dihydroxydibenzo-p-dioxin, 2,6-dihydroxythianthrene,2,7-dihydroxyphenoxathin, 2,7-dihydroxy-9,10-dimethylphenazine,3,6-dihydroxydibenzofuran, 3,6-dihydroxydibenzothiophene, and2,7-dihydroxycarbazole, resorcinol, substituted resorcinol compoundssuch as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl resorcinol,5-butyl resorcinol, 5-t-butyl resorcinol, 5-phenyl resorcinol, 5-cumylresorcinol, 2,4,5,6-tetrafluoro resorcinol, 2,4,5,6-tetrabromoresorcinol, or the like; catechol; hydroquinone; substitutedhydroquinones such as 2-methyl hydroquinone, 2-ethyl hydroquinone,2-propyl hydroquinone, 2-butyl hydroquinone, 2-t-butyl hydroquinone,2-phenyl hydroquinone, 2-cumyl hydroquinone, 2,3,5,6-tetramethylhydroquinone, 2,3,5,6-tetra-t-butyl hydroquinone, 2,3,5,6-tetrafluorohydroquinone, 2,3,5,6-tetrabromo hydroquinone, and the like, as well ascombinations comprising at least one of the foregoing dihydroxycompounds.

Specific examples of bisphenol compounds that may be represented byformula (3) include 1,1-bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl) propane(hereinafter “bisphenol A” or “BPA”), 2,2-bis(4-hydroxyphenyl) butane,2,2-bis(4-hydroxyphenyl) octane, 1,1-bis(4-hydroxyphenyl) propane,1,1-bis(4-hydroxyphenyl) n-butane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxy-t-butylphenyl) propane, and1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane (DMBPC). Combinationscomprising at least one of the foregoing dihydroxy compounds may also beused.

The dihydroxy compounds of formula (3) may be the following formula (8):

wherein R₃ and R₅ are each independently a halogen or a C₁₋₆ alkylgroup, R₄ is a C₁₋₆ alkyl, phenyl, or phenyl substituted with up to fivehalogens or C₁₋₆ alkyl groups, and c is 0 to 4. In a specificembodiment, R₄ is a C₁₋₆ alkyl or phenyl group. In still anotherembodiment, R₄ is a methyl or phenyl group. In another specificembodiment, each c is 0.

The dihydroxy compounds of formula (3) may be the following formula (9):

(also known as 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one(PPPBP)).

Alternatively, the dihydroxy compounds of formula (3) may be thefollowing formula (10):

(also known as 4,4′-(1-phenylethane-1,1-diyl)diphenol (bisphenol AP) or1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane).

Alternatively, the dihydroxy compounds of formula (3) may be thefollowing formula (11):

(bisphenol TMC) or 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane).

(2) Polyester Polycarbonates

The first polycarbonate may be a copolymer comprising different R1moieties in the carbonate. The copolymer may comprise other types ofpolymer units, such as ester units, and combinations comprising at leastone of homopolycarbonates and copolycarbonates as described above insection (1) of the first polycarbonate. A specific type of copolymer maybe a polyester carbonate, also known as a polyester-polycarbonate. Suchcopolymers further contain, in addition to recurring carbonate chainunits of the formula (1) as described above, repeating units of formula(12):

wherein O-D-O is a divalent group derived from a dihydroxy compound, andD may be, for example, one or more alkyl containing C₆-C₂₀ aromaticgroup(s), or one or more C₆-C₂₀ aromatic group(s), a C₂₋₁₀ alkylenegroup, a C₆₋₂₀ alicyclic group, a C₆₋₂₀ aromatic group or apolyoxyalkylene group in which the alkylene groups contain 2 to about 6carbon atoms, specifically 2, 3, or 4 carbon atoms; and T divalent groupderived from a dicarboxylic acid, and may be, for example, a C₂₋₁₀alkylene group, a C₆₋₂₀ alicyclic group, a C₆₋₂₀ alkyl aromatic group,or a C₆₋₂₀ aromatic group.

In one embodiment, D may be a C₂₋₃₀ alkylene group having a straightchain, branched chain, or cyclic (including polycyclic) structure. Inanother embodiment, O-D-O may be derived from an aromatic dihydroxycompound of formula (3) above. In another embodiment, O-D-O may bederived from an aromatic dihydroxy compound of formula (4) above. Inanother embodiment, O-D-O may be derived from an aromatic dihydroxycompound of formula (7) above.

Examples of aromatic dicarboxylic acids that may be used to prepare thepolyester units include isophthalic or terephthalic acid,1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether,4,4′-bisbenzoic acid, and combinations comprising at least one of theforegoing acids. Acids containing fused rings can also be present, suchas in 1,4-, 1,5-, or 2,6-naphthalenedicarboxylic acids. Specificdicarboxylic acids may be terephthalic acid, isophthalic acid,naphthalene dicarboxylic acid, cyclohexane dicarboxylic acid, orcombinations thereof. A specific dicarboxylic acid comprises acombination of isophthalic acid and terephthalic acid wherein the weightratio of isophthalic acid to terephthalic acid is about 91:9 to about2:98. In another embodiment, D may be a C₂₋₆ alkylene group and T isp-phenylene, m-phenylene, naphthalene, a divalent cycloaliphatic group,or a combination thereof. This class of polyester includes thepoly(alkylene terephthalates).

The molar ratio of ester units to carbonate units in the copolymers mayvary broadly, for example 1:99 to 99:1, specifically 10:90 to 90:10,more specifically 25:75 to 75:25, depending on the desired properties ofthe final composition.

In a specific embodiment, the polyester unit of apolyester-polycarbonate may be derived from the reaction of acombination of isophthalic and terephthalic diacids (or derivativesthereof) with resorcinol. In another embodiment, the polyester unit of apolyester-polycarbonate may be derived from the reaction of acombination of isophthalic acid and terephthalic acid with bisphenol-A.In an embodiment, the polycarbonate units may be derived from bisphenolA. In another specific embodiment, the polycarbonate units may bederived from resorcinol and bisphenol A in a molar ratio of resorcinolcarbonate units to bisphenol A carbonate units of 1:99 to 99:1.

Useful polyesters may include aromatic polyesters, poly(alkylene esters)including poly(alkylene arylates), and poly(cycloalkylene diesters).Aromatic polyesters may have a polyester structure according to formula(12), wherein D and T are each aromatic groups as described hereinabove.In an embodiment, useful aromatic polyesters may include, for example,poly(isophthalate-terephthalate-resorcinol) esters,poly(isophthalate-terephthalate-bisphenol-A) esters,poly[(isophthalate-terephthalate-resorcinol)ester-co-(isophthalate-terephthalate-bisphenol-A)]ester, or acombination comprising at least one of these.

(3) Functional Characteristics of the First Polycarbonate

The first polycarbonate may have a glass transition temperature (Tg) ofgreater than 170° C., 175° C., 180° C., 185° C., 190° C., 200° C., 210°C., 220° C., 230° C., 240° C., 250° C., 260° C., 270° C., 280° C., 290°C., or 300° C., as measured using a differential scanning calorimetrymethod.

The first polycarbonate may have a percent haze value of less than orequal to 10.0%, 8.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0%, 1.5%, or 0.5%as measured at a certain thickness according to ASTM D 1003-07. Thefirst polycarbonate may be measured at a 2.0, 2.2, 2.4, 2.6, 2.8, 3.0,3.2, 3.4, 3.6, 3.8, or a 4.0 millimeter thickness. The firstpolycarbonate may be measured at a 0.125 inch thickness. The firstpolycarbonate may have a light transmittance greater than or equal to50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, as measured at 3.2millimeters thickness according to ASTM D 1003-07. The firstpolycarbonate exhibits a heat resistance higher than the levels achievedwith BPA homopolymer as described in the Examples. In one embodiment,the first polycarbonate must have a glass transition temperature ofgreater than 170° C.

b. Second Polycarbonate—Siloxane

Described herein is the second polycarbonate of the polycarbonate blendcomposition. The second polycarbonate is a polycarbonate polysiloxanecopolymer. The polycarbonate polysiloxane copolymer has a polysiloxanestructural unit and a polycarbonate structural unit. The polycarbonatestructural unit of the polycarbonate polysiloxane copolymer may bederived from carbonate units of formula (1) as described above. Thecarbonate units may be derived from one or more dihydroxy monomers offormula (3) including bisphenol compound of formula (4), both asdescribed and incorporated herein from above. The dihydroxy compound maybe bisphenol-A.

The polysiloxane structural unit may be derived from asiloxane-containing dihydroxy compounds (also referred to herein as“hydroxyaryl end-capped polysiloxanes”) that contains diorganosiloxaneunits blocks of formula (13):

wherein each occurrence of R is same or different, and is a C₁₋₁₃monovalent organic group. For example, R can be a C₁-C₁₃ alkyl group,C₁-C₁₃ alkoxy group, C₂-C₁₃ alkenyl group, C₂-C₁₃ alkenyloxy group,C₃-C₆ cycloalkyl group, C₃-C₆ cycloalkoxy group, C₆-C₁₄ aryl group,C₆-C₁₀ aryloxy group, C₇-C₁₃ aralkyl group, C₇-C₁₃ aralkoxy group,C₇-C₁₃ alkylaryl group, or C₇-C₁₃ alkylaryloxy group. The foregoinggroups can be fully or partially halogenated with fluorine, chlorine,bromine, or iodine, or a combination thereof. In an embodiment, where atransparent polycarbonate is desired, R does not contain any halogen.Combinations of the foregoing R groups can be used in the samepolycarbonate.

The value of E in formula (13) can vary widely depending on the type andrelative amount of each of the different units in the polycarbonate, thedesired properties of the polycarbonate, and like considerations.Generally, E can have an average value of about 2 to about 1,000,specifically about 2 to about 500, more specifically about 2 to about100. In an embodiment, E has an average value of about 4 to about 90,specifically about 5 to about 80, and more specifically about 10 toabout 70. Where E is of a lower value, e.g., less than about 40, it canbe desirable to use a relatively larger amount of the units containingthe polysiloxane. Conversely, where E is of a higher value, e.g.,greater than about 40, it can be desirable to use a relatively loweramount of the units containing the polysiloxane.

In one embodiment, the polysiloxane blocks are provided by repeatingstructural units of formula (14):

wherein E is as defined above; each R is the same or different, and isas defined above; and each Ar is the same or different, and Ar is one ormore C₆-C₃₀ aromatic group(s), or one or more alkyl containing C₆-C₃₀aromatic group(s), wherein the bonds are directly connected to anaromatic moiety. —O—Ar—O— groups in formula (14) can be, for example, aC₆-C₃₀ dihydroxyaromatic compound. Combinations comprising at least oneof the foregoing dihydroxyaromatic compounds can also be used. Exemplarydihydroxyaromatic compounds are 1,1-bis(4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane,2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane,1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)n-butane,2,2-bis(4-hydroxy-1-methylphenyl)propane,1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl sulfide),1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and1,1-bis(4-hydroxy-t-butylphenyl)propane, or a combination comprising atleast one of the foregoing dihydroxy compounds.

Polycarbonates comprising such units can be derived from thecorresponding dihydroxy compound of formula (15):

wherein Ar and E are as described above. Compounds of formula (15) canbe obtained by the reaction of a dihydroxyaromatic compound with, forexample, an alpha, omega-bis-acetoxy-polydiorganosiloxane oligomer underphase transfer conditions. Compounds of formula (15) can also beobtained from the condensation product of a dihydroxyaromatic compound,with, for example, an alpha, omega bis-chloro-polydimethylsiloxaneoligomer in the presence of an acid scavenger.

In another embodiment, polydiorganosiloxane blocks comprises units offormula (16):

wherein R and E are as described above, and each R₆ is independently adivalent C₁-C₃₀ organic group such as a C₁-C₃₀ alkyl, C₁-C₃₀ aryl orC₁-C₃₀ alkylaryl. The polysiloxane blocks corresponding to formula (16)are derived from the corresponding dihydroxy compound of formula (17):

wherein R and E and R₆ are as described for formula (16).

In a specific embodiment, the second polycarbonate comprises carbonateunits derived from a polysiloxane monomer having the structure (17):

wherein E is an

average value of between 20 and 75.

In another specific embodiment the second polycarbonate comprisescarbonate units derived from a polysiloxane monomer having the structure(18):

wherein E is an average value of between 20 and 75.

In a specific embodiment, the polydiorganosiloxane blocks are providedby repeating structural units of formula (19)

wherein R and E are as defined above. R₇ in formula (19) is a divalentC₂-C₈ aliphatic group. Each M in formula (19) can be the same ordifferent, and is a halogen, cyano, nitro, C₁-C₈ alkylthio, C₁-C₈ alkyl,C₁-C₈ alkoxy, C₂-C₈ alkenyl, C₂-C₈ alkenyloxy group, C₃-C₈ cycloalkyl,C₃-C₈ cycloalkoxy, C₆-C₁₀ aryl, C₆-C₁₀ aryloxy, C₇-C₁₂ aralkyl, C₇-C₁₂aralkoxy, C₇-C₁₂ alkylaryl, or C₇-C₁₂ alkylaryloxy, wherein each n isindependently 0, 1, 2, 3, or 4.

In one embodiment, M of formula (19) is bromo or chloro, an alkyl groupsuch as methyl, ethyl, or propyl, an alkoxy group such as methoxy,ethoxy, or propoxy, or an aryl group such as phenyl, chlorophenyl, ortolyl, n=0 to 4; R₇ is a dimethylene, trimethylene or tetramethylenegroup; and R is a C₁₋₈ alkyl, haloalkyl such as trifluoropropyl,cyanoalkyl, or aryl such as phenyl, chlorophenyl or tolyl. In anotherembodiment, R is methyl, or a combination of methyl and trifluoropropyl,or a combination of methyl and phenyl. In still another embodiment, M ismethoxy, n is one, R₇ is a divalent C₁-C₃ aliphatic group, and R ismethyl.

Polysiloxane-polycarbonates comprising units of formula (19) can bederived from the corresponding dihydroxy polydiorganosiloxane (20):

wherein each of R, E, M, R₇, and n are as described above. Suchdihydroxy polysiloxanes can be made by effecting a platinum-catalyzedaddition between a siloxane hydride of formula (21):

wherein R and E are as previously defined, and an aliphaticallyunsaturated monohydric phenol. Exemplary aliphatically unsaturatedmonohydric phenols included, for example, eugenol, 2-allylphenol,4-allyl-2-methylphenol, 4-allyl-2-phenylphenol, 4-allyl-2-bromophenol,4-allyl-2-t-butoxyphenol, 4-phenyl-2-phenylphenol,2-methyl-4-propylphenol, 2-allyl-4,6-dimethylphenol,2-allyl-4-bromo-6-methylphenol, 2-allyl-6-methoxy-4-methylphenol,4-allylphenol, and 2-allyl-4,6-dimethylphenol. Combinations comprisingat least one of the foregoing can also be used.

(1) Polysiloxane-Polycarbonate Blends

In an embodiment, the polysiloxane-polycarbonate can comprisepolysiloxane blocks, which may or may not be derived from thecorresponding dihydroxy polysiloxane compound, present in an amount of0.15 wt % to 30 wt %, 0.5 wt % to 25 wt %, 1 to 20 wt %, 5 wt % to 7 wt%, 4 wt % to 6 wt %, or 4 wt % to 8 wt % based on the total weight ofpolysiloxane blocks and carbonate units or the total weight of the blendcomposition. In a specific embodiment, the polysiloxane blocks arepresent in an amount of 1 to 10 wt %, specifically 2 to 9 wt %, and morespecifically 3 to 8 wt %, based on the total weight of polysiloxaneblocks and carbonate units.

In an embodiment, the carbonate units comprising thepolysiloxane-polycarbonate are present in an amount of 70 wt % to 99.85wt %, specifically 75 wt % to 99.5 wt %, and more specifically 80 wt %to 99 wt % based on the total weight of polysiloxane blocks andcarbonate units. In a specific embodiment, the carbonate units arepresent in an amount of 90 wt % to 99 wt %, specifically 91 wt % to 98wt %, and more specifically 92 wt % to 97 wt %, based on the totalweight of polysiloxane blocks and carbonate units.

The polysiloxane-polycarbonate may be a blend of4,4′-dihydroxy-2,2-diphenylpropane) with a block copolymer ofpolycarbonate and eugenol capped polydimethylsilioxane (PDMS) having thestructure as shown below:

c. Functional Characteristics of the Second Polycarbonate

The second polycarbonate may have a percent haze value of less than orequal to 10.0%, 8.0%, 6.0%, 5.0%, 4.0%, 3.0%, 2.0%, 1.0%, 1.5%, or 0.5%as measured at 3.2 millimeters thickness according to ASTM D 1003-07.The second polycarbonate may have a percent haze value of less than orequal to 3.0% as measured at 3.2 millimeters thickness according to ASTMD 1003-07. The second polycarbonate may exhibit 100% ductility at −20°C. as measured using the method of ASTM D 256-10. The secondpolycarbonate may be measured at a 0.125 inch thickness.

3. Method of Making First and Second Polycarbonates

Polycarbonates can be manufactured by processes such as interfacialpolymerization and melt polymerization. High Tg copolycarbonates aregenerally manufactured using interfacial polymerization. Although thereaction conditions for interfacial polymerization can vary, anexemplary process generally involves dissolving or dispersing a dihydricphenol reactant in aqueous caustic soda or potash, adding the resultingmixture to a water-immiscible solvent medium, and contacting thereactants with a carbonate precursor in the presence of a catalyst suchas, for example, a tertiary amine or a phase transfer catalyst, undercontrolled pH conditions, e.g., 8 to 10. The most commonly used waterimmiscible solvents include methylene chloride, 1,2-dichloroethane,chlorobenzene, toluene, and the like.

Exemplary carbonate precursors include, for example, a carbonyl halidesuch as carbonyl bromide or carbonyl chloride, or a haloformate such asa bishaloformates of a dihydric phenol (e.g., the bischloroformates ofbisphenol A, hydroquinone, or the like) or a glycol (e.g., thebishaloformate of ethylene glycol, neopentyl glycol, polyethyleneglycol, or the like). Combinations comprising at least one of theforegoing types of carbonate precursors can also be used. In anexemplary embodiment, an interfacial polymerization reaction to formcarbonate linkages uses phosgene as a carbonate precursor, and isreferred to as a phosgenation reaction.

Among tertiary amines that can be used are aliphatic tertiary aminessuch as triethylamine, tributylamine, cycloaliphatic amines such asN,N-diethyl-cyclohexylamine and aromatic tertiary amines such asN,N-dimethylaniline.

Among the phase transfer catalysts that can be used are catalysts of theformula (R³)₄Q⁺X, wherein each R³ is the same or different, and is aC₁₋₁₀ alkyl group; Q is a nitrogen or phosphorus atom; and X is ahalogen atom or a C₁₋₈ alkoxy group or C₆₋₁₈ aryloxy group. Exemplaryphase transfer catalysts include, for example, [CH₃(CH₂)₃]₄NX,[CH₃(CH₂)₃]₄PX, [CH₃(CH₂)₅]₄NX, [CH₃(CH₂)₆]₄NX, [CH₃(CH₂)₄]₄NX,CH₃[CH₃(CH₂)₃]₃NX, and CH₃[CH₃(CH₂)₂]₃NX, wherein X is Cl⁻, Br⁻, a C₁₋₈alkoxy group or a C₆₋₁₈ aryloxy group. An effective amount of a phasetransfer catalyst can be 0.1 to 10 wt % based on the weight of bisphenolin the phosgenation mixture. In another embodiment an effective amountof phase transfer catalyst can be 0.5 to 2 wt % based on the weight ofbisphenol in the phosgenation mixture.

The polycarbonate may be prepared by a melt polymerization process.Generally, in the melt polymerization process, polycarbonates areprepared by co-reacting, in a molten state, the dihydroxy reactant(s)(i.e. aliphatic diol and/or aliphatic diacid, and any additionaldihydroxy compound) and a diaryl carbonate ester, such as diphenylcarbonate, or more specifically in an embodiment, an activated carbonatesuch as bis(methyl salicyl) carbonate, in the presence of atransesterification catalyst. The reaction may be carried out in typicalpolymerization equipment, such as one or more continuously stirredreactors (CSTR's), plug flow reactors, wire wetting fall polymerizers,free fall polymerizers, wiped film polymerizers, BANBURY® mixers, singleor twin screw extruders, or combinations of the foregoing. Volatilemonohydric phenol is removed from the molten reactants by distillationand the polymer is isolated as a molten residue. A specifically usefulmelt process for making polycarbonates uses a diaryl carbonate esterhaving electron-withdrawing substituents on the aryls. Examples ofspecifically useful diaryl carbonate esters with electron withdrawingsubstituents include bis(4-nitrophenyl)carbonate,bis(2-chlorophenyl)carbonate, bis(4-chlorophenyl)carbonate, bis(methylsalicyl)carbonate, bis(4-methylcarboxylphenyl)carbonate,bis(2-acetylphenyl)carboxylate, bis(4-acetylphenyl)carboxylate, or acombination comprising at least one of the foregoing.

a. End Capping Agent

All types of polycarbonate end groups are contemplated as being usefulin the high and low Tg polycarbonates, provided that such end groups donot significantly adversely affect desired properties of thecompositions. An end-capping agent (also referred to as a chain-stopper)can be used to limit molecular weight growth rate, and so controlmolecular weight of the first and/or second polycarbonate. Exemplarychain-stoppers include certain monophenolic compounds (i.e., phenylcompounds having a single free hydroxy group), monocarboxylic acidchlorides, and/or monochloroformates. Phenolic chain-stoppers areexemplified by phenol and C₁-C₂₂ alkyl-substituted phenols such asp-cumyl-phenol, resorcinol monobenzoate, and p- and tertiary-butylphenol, cresol, and monoethers of diphenols, such as p-methoxyphenol.Alkyl-substituted phenols with branched chain alkyl substituents having8 to 9 carbon atoms can be specifically mentioned.

Endgroups can derive from the carbonyl source (i.e., the diarylcarbonate), from selection of monomer ratios, incomplete polymerization,chain scission, and the like, as well as any added end-capping groups,and can include derivatizable functional groups such as hydroxy groups,carboxylic acid groups, or the like. In an embodiment, the endgroup of apolycarbonate can comprise a structural unit derived from a diarylcarbonate, where the structural unit can be an endgroup. In a furtherembodiment, the endgroup is derived from an activated carbonate. Suchendgroups can derive from the transesterification reaction of the alkylester of an appropriately substituted activated carbonate, with ahydroxy group at the end of a polycarbonate polymer chain, underconditions in which the hydroxy group reacts with the ester carbonylfrom the activated carbonate, instead of with the carbonate carbonyl ofthe activated carbonate. In this way, structural units derived fromester containing compounds or substructures derived from the activatedcarbonate and present in the melt polymerization reaction can form esterendgroups. In an embodiment, the ester endgroup derived from a salicylicester can be a residue of BMSC or other substituted or unsubstitutedbis(alkyl salicyl) carbonate such as bis(ethyl salicyl) carbonate,bis(propyl salicyl) carbonate, bis(phenyl salicyl) carbonate, bis(benzylsalicyl) carbonate, or the like. In a specific embodiment, where BMSC isused as the activated carbonyl source, the endgroup is derived from andis a residue of BMSC, and is an ester endgroup derived from a salicylicacid ester, having the structure of formula (22):

The reactants for the polymerization reaction using an activatedaromatic carbonate can be charged into a reactor either in the solidform or in the molten form. Initial charging of reactants into a reactorand subsequent mixing of these materials under reactive conditions forpolymerization may be conducted in an inert gas atmosphere such as anitrogen atmosphere. The charging of one or more reactant may also bedone at a later stage of the polymerization reaction. Mixing of thereaction mixture is accomplished by any methods known in the art, suchas by stifling. Reactive conditions include time, temperature, pressureand other factors that affect polymerization of the reactants. Typicallythe activated aromatic carbonate is added at a mole ratio of 0.8 to 1.3,and more preferably 0.9 to 1.3, and all sub-ranges there between,relative to the total moles of monomer unit compounds. In a specificembodiment, the molar ratio of activated aromatic carbonate to monomerunit compounds is 1.013 to 1.29, specifically 1.015 to 1.028. In anotherspecific embodiment, the activated aromatic carbonate is BMSC.

b. Branching Groups

Polycarbonates with branching groups are also contemplated as beinguseful, provided that such branching does not significantly adverselyaffect desired properties of the polycarbonate. Branched polycarbonateblocks can be prepared by adding a branching agent duringpolymerization. These branching agents include polyfunctional organiccompounds containing at least three functional groups selected fromhydroxyl, carboxyl, carboxylic anhydride, haloformyl, and mixtures ofthe foregoing functional groups. Specific examples include trimelliticacid, trimellitic anhydride, trimellitic trichloride, tris-p-hydroxyphenyl ethane, isatin-bis-phenol, tris-phenol TC(1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene), tris-phenol PA(4(4(1,1-bis(p-hydroxyphenyl)-ethyl)alpha, alpha-dimethylbenzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid, andbenzophenone tetracarboxylic acid. The branching agents can be added ata level of about 0.05 to about 2.0 wt %. Mixtures comprising linearpolycarbonates and branched polycarbonates can be used.

4. Other Additives

a. Impact Modifiers

The polycarbonate blend composition may further comprise impactmodifiers. For example, the composition can further include impactmodifier(s), with the proviso that the additives are selected so as tonot significantly adversely affect the desired properties of thecomposition. Suitable impact modifiers may be high molecular weightelastomeric materials derived from olefins, monovinyl aromatic monomers,acrylic and methacrylic acids and their ester derivatives, as well asconjugated dienes. The polycarbonate blend composition formed fromconjugated dienes can be fully or partially hydrogenated. Theelastomeric materials can be in the form of homopolymers or copolymers,including random, block, radial block, graft, and core-shell copolymers.Combinations of impact modifiers may be used.

A specific type of impact modifier may be an elastomer-modified graftcopolymer comprising (i) an elastomeric (i.e., rubbery) polymersubstrate having a Tg less than about 10° C., less than about 0° C.,less than about −10° C., or between about −40° C. to −80° C., and (ii) arigid polymer grafted to the elastomeric polymer substrate. Materialssuitable for use as the elastomeric phase include, for example,conjugated diene rubbers, for example polybutadiene and polyisoprene;copolymers of a conjugated diene with less than about 50 wt % of acopolymerizable monomer, for example a monovinylic compound such asstyrene, acrylonitrile, n-butyl acrylate, or ethyl acrylate; olefinrubbers such as ethylene propylene copolymers (EPR) orethylene-propylene-diene monomer rubbers (EPDM); ethylene-vinyl acetaterubbers; silicone rubbers; elastomeric C₁₋₈ alkyl(meth)acrylates;elastomeric copolymers of C₁₋₈ alkyl(meth)acrylates with butadieneand/or styrene; or combinations comprising at least one of the foregoingelastomers. Materials suitable for use as the rigid phase include, forexample, monovinyl aromatic monomers such as styrene and alpha-methylstyrene, and monovinylic monomers such as acrylonitrile, acrylic acid,methacrylic acid, and the C₁-C₆ esters of acrylic acid and methacrylicacid, specifically methyl methacrylate.

Specific impact modifiers include styrene-butadiene-styrene (SBS),styrene-butadiene rubber (SBR), styrene-ethylene-butadiene-styrene(SEBS), ABS (acrylonitrile-butadiene-styrene),acrylonitrile-ethylene-propylene-diene-styrene (AES),styrene-isoprene-styrene (SIS), methyl methacrylate-butadiene-styrene(MBS), and styrene-acrylonitrile (SAN). Exemplary elastomer-modifiedgraft copolymers include those formed from styrene-butadiene-styrene(SBS), styrene-butadiene rubber (SBR),styrene-ethylene-butadiene-styrene (SEBS), ABS(acrylonitrile-butadiene-styrene),acrylonitrile-ethylene-propylene-diene-styrene (AES),styrene-isoprene-styrene (SIS), methyl methacrylate-butadiene-styrene(MBS), and styrene-acrylonitrile (SAN).

MBS may be derived from the following monomers:

SEBS may be a linear triblockcopolymer based on styrene andethylene/butylene. Each copolymer chain that may consist of threeblocks: a middle block that is a random ethylene/butylene copolymersurrounded by two blocks of polystyrene. The SEBS may bestyrene-b-(ethylene-co-butylene)-b-styrene polymer.

Impact modifiers may be present in amounts of 1 to 30 parts by weight,based on 100 parts by weight of copolycarbonate,polysiloxane-polycarbonate, and any additional polymer. Impact modifiersmay include MBS and SBS.

b. UV Stabilizers

The polycarbonate blend composition may further comprise a UV stabilizerfor improved performance in UV stabilization. UV stabilizers dispersethe UV radiation energy.

UV stabilizers may be hydroxybenzophenones, hydroxyphenylbenzotriazoles, cyanoacrylates, oxanilides, and hydroxyphenyl triazines.UV stabilizers may include, but are not limited to,poly[(6-morphilino-s-triazine-2,4-diyl)[2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino],2-hydroxy-4-octloxybenzophenoe (Uvinul®3008),6-tert-butyl-2-(5-chloro-2H-benzotriazole-2-yl)-4-methylphenyl (Uvinul®3026), 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazole-2-yl)-phenol(Uvinul®3027), 2-(2H-benzotriazole-2-yl)-4,6-di-tert-pentylphenol(Uvinul®3028),2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (Uvinul®3029),1,3-bis[(2′cyano-3′,3′-diphenylacryloyl)oxy]-2,2-bis-[{[2′-cyano-3′,3′-diphenylacryloyl)oxy]methyl}-propane(Uvinul® 3030), 2-(2H-benzotriazole-2-yl)-4-methylphenol (Uvinul® 3033),2-(2H-bezhotriazole-2-yl)-4,6-bis(1-methyl-1-phenyethyl)phenol (Uvinul®3034), ethyl-2-cyano-3,3-diphenylacrylate (Uvinul® 3035),(2-ethylhexyl)-2-cyano-3,3-diphenylacrylate (Uvinul® 3039),N,N′-bisformyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)hexamethylendiamine(Uvinul® 4050H), bis-(2,2,6,6-tetramethyl-4-pipieridyl)-sebacate(Uvinul® 4077H),bis-(1,2,2,6,6-pentamethyl-4-piperdiyl)-sebacate+methyl-(1,2,2,6,6-pentamethyl-4-piperidyl)-sebacate(Uvinul® 4092H) or combination thereof.

The polycarbonate blend composition may comprise one or more UVstabilizers, including Cyasorb 5411, Cyasorb UV-3638, Uvinul 3030,and/or Tinuvin 234.

Certain monophenolic UV absorbers, which can also be used as cappingagents, can be utilized as one or more additives; for example,4-substituted-2-hydroxybenzophenones and their derivatives, arylsalicylates, monoesters of diphenols such as resorcinol monobenzoate,2-(2-hydroxyaryl)-benzotriazoles and their derivatives,2-(2-hydroxyaryl)-1,3,5-triazines and their derivatives, and the like.

c. Colorants

Colorants such as pigment and/or dye additives may be present in thecomposition. Useful pigments can include, for example, inorganicpigments such as metal oxides and mixed metal oxides such as zinc oxide,titanium dioxides, iron oxides, or the like; sulfides such as zincsulfides, or the like; aluminates; sodium sulfo-silicates sulfates,chromates, or the like; carbon blacks; zinc ferrites; ultramarine blue;organic pigments such as azos, di-azos, quinacridones, perylenes,naphthalene tetracarboxylic acids, flavanthrones, isoindolinones,tetrachloroisoindolinones, anthraquinones, enthrones, dioxazines,phthalocyanines, and azo lakes; Pigment Red 101, Pigment Red 122,Pigment Red 149, Pigment Red 177, Pigment Red 179, Pigment Red 202,Pigment Violet 29, Pigment Blue 15, Pigment Blue 60, Pigment Green 7,Pigment Yellow 119, Pigment Yellow 147, Pigment Yellow 150, and PigmentBrown 24; or combinations comprising at least one of the foregoingpigments. Pigments are generally used in amounts of 0.01 to 10 parts byweight, based on 100 parts by weight of the polymer component of thethermoplastic composition.

Exemplary dyes are generally organic materials and include, for example,coumarin dyes such as coumarin 460 (blue), coumarin 6 (green), nile redor the like; lanthanide complexes; hydrocarbon and substitutedhydrocarbon dyes; polycyclic aromatic hydrocarbon dyes; scintillationdyes such as oxazole or oxadiazole dyes; aryl- or heteroaryl-substitutedpoly (C₂₋₈) olefin dyes; carbocyanine dyes; indanthrone dyes;phthalocyanine dyes; oxazine dyes; carbostyryl dyes;napthalenetetracarboxylic acid dyes; porphyrin dyes; bis(styryl)biphenyldyes; acridine dyes; anthraquinone dyes; cyanine dyes; methine dyes;arylmethane dyes; azo dyes; indigoid dyes, thioindigoid dyes, diazoniumdyes; nitro dyes; quinone imine dyes; aminoketone dyes; tetrazoliumdyes; thiazole dyes; perylene dyes, perinone dyes;bis-benzoxazolylthiophene (BBOT); triarylmethane dyes; xanthene dyes;thioxanthene dyes; naphthalimide dyes; lactone dyes; fluorophores suchas anti-stokes shift dyes which absorb in the near infrared wavelengthand emit in the visible wavelength, or the like; luminescent dyes suchas 7-amino-4-methylcoumarin;3-(2′-benzothiazolyl)-7-diethylaminocoumarin;2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole;2,5-bis-(4-biphenylyl)-oxazole; 2,2′-dimethyl-p-quaterphenyl;2,2-dimethyl-p-terphenyl; 3,5,3″″,5″″-tetra-t-butyl-p-quinquephenyl;2,5-diphenylfuran; 2,5-diphenyloxazole; 4,4′-diphenylstilbene;4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran;1,1′-diethyl-2,2′-carbocyanine iodide;3,3′-diethyl-4,4′,5,5′-dibenzothiatricarbocyanine iodide;7-dimethylamino-1-methyl-4-methoxy-8-azaquinolone-2;7-dimethylamino-4-methylquinolone-2;2-(4-(4-dimethylaminophenyl)-1,3-butadienyl)-3-ethylbenzothiazoliumperchlorate; 3-diethylamino-7-diethyliminophenoxazonium perchlorate;2-(1-naphthyl)-5-phenyloxazole; 2,2′-p-phenylen-bis(5-phenyloxazole);rhodamine 700; rhodamine 800; pyrene, chrysene, rubrene, coronene, orthe like; or combinations comprising at least one of the foregoing dyes.Dyes are generally used in amounts of 0.01 to 10 parts by weight, basedon 100 parts by weight of the polycarbonate component of the blendcomposition.

d. Flame Retardants

Various types of flame retardants can also be utilized as additives. Inone embodiment, the flame retardant additives include, for example,flame retardant salts such as alkali metal salts of perfluorinated C₁₋₁₆alkyl sulfonates such as potassium perfluorobutane sulfonate (Rimarsalt), potassium perfluoroctane sulfonate, tetraethylammoniumperfluorohexane sulfonate, potassium diphenylsulfone sulfonate (KSS),and the like, sodium benzene sulfonate, sodium toluene sulfonate (NATS)and the like; and salts formed by reacting for example an alkali metalor alkaline earth metal (for example lithium, sodium, potassium,magnesium, calcium and barium salts) and an inorganic acid complex salt,for example, an oxo-anion, such as alkali metal and alkaline-earth metalsalts of carbonic acid, such as Na₂CO₃, K₂CO₃, MgCO₃, CaCO₃, and BaCO₃or fluoro-anion complex such as Li₃AlF₆, BaSiF₆, KBF₄, K₃AlF₆, KAlF₄,K₂SiF₆, and/or Na₃AlF₆ or the like. Rimar salt and KSS and NATS, aloneor in combination with other flame retardants, are particularly usefulin the polycarbonate compositions disclosed herein.

In another embodiment, the flame-retardants are selected from at leastone of the following: alkali metal salts of perfluorinated C₁₋₁₆ alkylsulfonates; potassium perfluorobutane sulfonate; potassiumperfluoroctane sulfonate; tetraethylammonium perfluorohexane sulfonate;and potassium diphenylsulfone sulfonate.

In another embodiment, the flame retardant is not a bromine or chlorinecontaining composition.

In another embodiment, the flame retardant additives include organiccompounds that include phosphorus, bromine, and/or chlorine.Non-brominated and non-chlorinated phosphorus-containing flameretardants can be used in certain applications for regulatory reasons,for example organic phosphates and organic compounds containingphosphorus-nitrogen bonds. One type of exemplary organic phosphate is anaromatic phosphate of the formula (GO)₃P═O, wherein each G isindependently an alkyl, cycloalkyl, aryl, alkylaryl, or arylalkyl group,provided that at least one G is an aromatic group. Two of the G groupscan be joined together to provide a cyclic group, for example, diphenylpentaerythritol diphosphate. Exemplary aromatic phosphates include,phenyl bis(dodecyl) phosphate, phenyl bis(neopentyl) phosphate, phenylbis(3,5,5′-trimethylhexyl) phosphate, ethyl diphenyl phosphate,2-ethylhexyl di(p-tolyl) phosphate, bis(2-ethylhexyl) p-tolyl phosphate,tritolyl phosphate, bis(2-ethylhexyl)phenyl phosphate, tri(nonylphenyl)phosphate, bis(dodecyl) p-tolyl phosphate, dibutyl phenyl phosphate,2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5′-trimethylhexyl)phosphate, 2-ethylhexyl diphenyl phosphate, or the like. A specificaromatic phosphate is one in which each G is aromatic, for example,triphenyl phosphate, tricresyl phosphate, isopropylated triphenylphosphate, and the like.

Di- or poly-functional aromatic phosphorus-containing compounds are alsouseful as additives, for example, compounds of the formulas below:

wherein each G¹ is independently a hydrocarbon having 1 to 30 carbonatoms; each G² is independently a hydrocarbon or hydrocarbonoxy having 1to 30 carbon atoms; each X is independently a bromine or chlorine; m is0 to 4, and n is 1 to 30. Exemplary di- or polyfunctional aromaticphosphorus-containing compounds include resorcinol tetraphenyldiphosphate (RDP), the bis(diphenyl) phosphate of hydroquinone and thebis(diphenyl) phosphate of bisphenol-A, respectively, their oligomericand polymeric counterparts, and the like.

Exemplary flame retardant additives containing phosphorus-nitrogen bondsinclude phosphonitrilic chloride, phosphorus ester amides, phosphoricacid amides, phosphonic acid amides, phosphinic acid amides,tris(aziridinyl) phosphine oxide.

The flame retardant additive may have formula (26):

wherein R is a C₁₋₃₆ alkylene, alkylidene or cycloaliphatic linkage,e.g., methylene, ethylene, propylene, isopropylene, isopropylidene,butylene, isobutylene, amylene, cyclohexylene, cyclopentylidene, or thelike; or an oxygen ether, carbonyl, amine, or a sulfur-containinglinkage, e.g., sulfide, sulfoxide, sulfone, or the like. R can alsoconsist of two or more alkylene or alkylidene linkages connected by suchgroups as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone,or the like.

Ar and Ar′ in formula (26) are each independently mono- orpolycarbocyclic aromatic groups such as phenylene, biphenylene,terphenylene, naphthylene, or the like.

Y is an organic, inorganic, or organometallic radical, for example (1)halogen, e.g., chlorine, bromine, iodine, fluorine or (2) ether groupsof the general formula OB, wherein B is a monovalent hydrocarbon groupsimilar to X or (3) monovalent hydrocarbon groups of the typerepresented by R or (4) other substituents, e.g., nitro, cyano, and thelike, said substituents being essentially inert provided that there isgreater than or equal to one, specifically greater than or equal to two,halogen atoms per aryl nucleus. One or both of Ar and Ar′ may furtherhave one or more hydroxyl substituents.

When present, each X is independently a monovalent hydrocarbon group,for example an alkyl group such as methyl, ethyl, propyl, isopropyl,butyl, decyl, or the like; an aryl groups such as phenyl, naphthyl,biphenyl, xylyl, tolyl, or the like; and aralkyl group such as benzyl,ethylphenyl, or the like; a cycloaliphatic group such as cyclopentyl,cyclohexyl, or the like. The monovalent hydrocarbon group can itselfcontain inert substituents.

Each d is independently 1 to a maximum equivalent to the number ofreplaceable hydrogens substituted on the aromatic rings comprising Ar orAr′. Each e is independently 0 to a maximum equivalent to the number ofreplaceable hydrogens on R. Each a, b, and c is independently a wholenumber, including 0. When b is not 0, neither a nor c can be 0.Otherwise either a or c, but not both, can be 0. Where b is 0, thearomatic groups are joined by a direct carbon-carbon bond.

The hydroxyl and Y substituents on the aromatic groups, Ar and Ar′ canbe varied in the ortho, meta or para positions on the aromatic rings andthe groups can be in any possible geometric relationship with respect toone another.

Included within the scope of polymeric or oligomeric flame retardantsderived from mono or dihydroxy derivatives of formula (26) are:2,2-bis-(3,5-dichlorophenyl)-propane; bis-(2-chlorophenyl)-methane;bis(2,6-dibromophenyl)-methane; 1,1-bis-(4-iodophenyl)-ethane;1,2-bis-(2,6-dichlorophenyl)-ethane;1,1-bis-(2-chloro-4-iodophenyl)ethane;1,1-bis-(2-chloro-4-methylphenyl)-ethane;1,1-bis-(3,5-dichlorophenyl)-ethane;2,2-bis-(3-phenyl-4-bromophenyl)-ethane;2,6-bis-(4,6-dichloronaphthyl)-propane;2,2-bis-(2,6-dichlorophenyl)-pentane;2,2-bis-(3,5-dibromophenyl)-hexane; bis-(4-chlorophenyl)-phenyl-methane;bis-(3,5-dichlorophenyl)-cyclohexylmethane;bis-(3-nitro-4-bromophenyl)-methane;bis-(4-hydroxy-2,6-dichloro-3-methoxyphenyl)-methane; and2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane 2,2bis-(3-bromo-4-hydroxyphenyl)-propane. Also included within the abovestructural formula are: 1,3-dichlorobenzene, 1,4-dibromobenzene,1,3-dichloro-4-hydroxybenzene, and biphenyls such as2,2′-dichlorobiphenyl, polybrominated 1,4-diphenoxybenzene,2,4′-dibromobiphenyl, and 2,4′-dichlorobiphenyl as well as decabromodiphenyl oxide, and the like.

Another useful class of flame retardant is the class of cyclic siloxaneshaving the general formula (R₂SiO)y wherein R is a monovalenthydrocarbon or fluorinated hydrocarbon having from 1 to 18 carbon atomsand y is a number from 3 to 12. Examples of fluorinated hydrocarboninclude, but are not limited to, 3-fluoropropyl, 3,3,3-trifluoropropyl,5,5,5,4,4,3,3-heptafluoropentyl, fluorophenyl, difluorophenyl andtrifluorotolyl. Examples of suitable cyclic siloxanes include, but arenot limited to, octamethylcyclotetrasiloxane,1,2,3,4-tetramethyl-1,2,3,4-tetravinylcyclotetrasiloxane,1,2,3,4-tetramethyl-1,2,3,4-tetraphenylcyclotetrasiloxane,octaethylcyclotetrasiloxane, octapropylcyclotetrasiloxane,octabutylcyclotetrasiloxane, decamethylcyclopentasiloxane,dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane,hexadecamethylcyclooctasiloxane, eicosamethylcyclodecasiloxane,octaphenylcyclotetrasiloxane, and the like. A particularly useful cyclicsiloxane is octaphenylcyclotetrasiloxane.

When present, the foregoing flame retardant additives are generallypresent in amounts of 0.01 to 10 wt %, more specifically 0.02 to 5 wt %,based on 100 parts by weight of the polymer component of thethermoplastic composition.

In addition to the flame retardant, for example, the herein describedpolycarbonates and blends can include various additives ordinarilyincorporated in polycarbonate compositions, with the proviso that theadditives are selected so as to not significantly adversely affect thedesired properties of the polycarbonate, such as transparency.Combinations of additives can be used. Such additives can be mixed at asuitable time during the mixing of the components for forming thepolycarbonate and/or blend.

e. Heat Stabilizers

Exemplary heat stabilizer additives include, for example,organophosphites such as triphenyl phosphite,tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono- anddi-nonylphenyl)phosphite or the like; phosphonates such asdimethylbenzene phosphonate or the like, phosphates such as trimethylphosphate, or the like, or combinations comprising at least one of theforegoing heat stabilizers. Heat stabilizers are generally used inamounts of 0.0001 to 1 part by weight, based on 100 parts by weight ofthe polymer component of the thermoplastic composition.

5. Mixers and Extruders

The polycarbonate blend composition can be manufactured by variousmethods. For example, the first and second polycarbonates may be firstblended in a high speed HENSCHEL-Mixer®. Other low shear processes,including but not limited to hand mixing, can also accomplish thisblending. The blend may then be fed into the throat of a single ortwin-screw extruder via a hopper. Alternatively, at least one of thecomponents can be incorporated into the composition by feeding directlyinto the extruder at the throat and/or downstream through a sidestuffer.Additives can also be compounded into a masterbatch with a desiredpolymeric resin and fed into the extruder. The extruder is generallyoperated at a temperature higher than that necessary to cause thecomposition to flow. The extrudate is immediately quenched in a waterbatch and pelletized. The pellets, so prepared, when cutting theextrudate can be one-fourth inch long or less as desired. Such pelletscan be used for subsequent molding, shaping, or forming.

6. Articles

Shaped, formed, or molded articles comprising the polycarbonate resincompositions are provided herein. The compositions can be molded intouseful shaped articles by a variety of means such as injection molding,extrusion, rotational molding, blow molding and thermoforming to formarticles such as, for example, various components for cell phones andcell phone covers, components for computer housings, computer housingsand business machine housings such as housings for monitors, handheldelectronic device housings such as housings for cell phones, electricalconnectors, and components of lighting fixtures, ornaments, homeappliances, roofs, greenhouses, sun rooms, swimming pool enclosures,Light Emitting Diodes (LEDs) and light panels, extruded film and sheetarticles, and the like. The compositions are of particular utility inthe manufacture of thin walled articles such as housings for electronicdevices. Additional examples of articles that can be formed from thecompositions include electrical parts, such as relays, and enclosures,consumer electronics such as enclosures and parts for laptops, desktops,docking stations, PDAs, digital cameras, desktops, andtelecommunications parts such as parts for base station terminals.

Example 1 Polycarbonate/Polysiloxane Compositions and CharacteristicsThereof

Various polycarbonate blends according to the Formulations specifiedbelow in Table 1 were tested for various attributes such as heatresistance, ductility, impact strength, and transparency and the resultsare shown in Table 2.

TABLE 1 Formulation 1 2 3 4 5 6 7 8 PC-polysiloxane resin 85 75 85 75 —— — — PC-1 resin — — 5 8.3 57 50 100 67 PC-2 resin — — 10 16.7 28 25 —33 XHT resin 15 25 — — 15 25 — —

The weight-averaged molecular weights (Mw) of the resins listed in Table1 were all measured by a standard gel permeation chromatography methodusing Bisphenol-A polycarbonate standards. The PC-polysiloxane resin ofTable 1 is a polycarbonate-siloxane co-polymer, which has a molecularweight of 23,000 and contains 6% siloxane. Such a resin may be made bythe method described in U.S. Pat. No. 6,833,422, which is hereinincorporated by reference in its entirety.

The PC-1 resin of Table 1 is a 2,2-bis(4-hydroxyphenyl)propanepolycarbonate resin, which is cumyl phenol end capped. The PC-1 resinhas a molecular weight (Mw) of 30,000 and a Tg of 149° C.

The PC-2 resin of Table 1 is a 2,2-bis(4-hydroxyphenyl)propanepolycarbonate resin, which is cumyl phenol end capped. The PC-2 resinhas a molecular weight (Mw) of 22,000 and a Tg of 148° C.

The XHT resin of Table 1 is a polycarbonate consisting of 33 mole % of3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP) and 67 mole %2,2-bis(4-hydroxyphenyl)propane. The XHT resin has a molecular weight(Mw) of 23,000 and a Tg of 198° C.

TABLE 2 Formulation Characteristics and Properties Formulation (1) (2)(3) (4) (5) (6) (7) (8) Glass Transition Temp (Tg) 150.1 152.1 143.9145.5 155.9 159.8 150.1 148.6 MVR-360 cm3/10 min. 8.38 7.57 11.4 12.58.07 7.77 6.79 10.2 % T std % 82.4 77.4 85.5 85.2 89.7 89.6 89.9 89.8 %haze std % 2.74 5.93 1.57 1.61 0.28 0.29 0.21 0.3 Cnd: Temperature/1° C.−10 −10 −10 −10 −10 −10 −10 −10 Ductility/0% 100 0 100 100 0 0 100 100Impact Strength-Avg/0 J/M 594 495 709 713 231 146 803 823 Cnd:Temperature/1° C. −20 −20 −20 −20 −20 −20 −20 −20 Ductility/0% 100 0 100100 0 0 0 0 Impact Strength-Avg/0 J/M 579 471 700 728 157 136 852 182Cnd: Temperature/1° C. −30 −30 −30 −30 −30 −30 −30 −30 Ductility/0% 0 0100 100 0 0 0 0 Impact Strength-Avg/0 J/M 512 394 686 688 134 128 318150 Cnd: Temperature/1° C. −40 −40 −40 −40 −40 −40 −40 −40 Ductility/0%0 0 0 0 0 0 0 0 Impact Strength-Avg/0 J/M 482 248 646 655 133 118 156138

All Formulations were prepared by dry blending and extruded with aWerner Pfeidlere 30 mm twin screw at a temperature profile of 520° F. to550° F. and cutting into pellets, and injection molding at 540° F. to580° F.

A glass transition temperature test was conducted with each of theFormulations. Measurement of glass transition temperature (row 2) foreach of the formulations indicated that the PC-polysiloxane resin/XHTresin blends (Formulations 1 and 2) do not significantly differ from theglass transition temperature of polycarbonate resins (Formulations 7 and8).

Similarly, a melt volume flow rate test (MVR) was conducted using ASTM D1238-10 at 1.2 kg at 300° C. MVR data indicates that with the exceptionof Formulation 2 (75% PC-polysiloxane/25% XHT) and Formulation 7 (lowmelt flow polycarbonate PC-1), the PC-polysiloxane/XHT blends meet thetargeted 8 to 12 standard. Formulation 2 was only slightly below thetargeted 8 standard.

Formulations 1 and 2 exhibited only slightly deteriorated opticalperformance vs standard PC-polysiloxane resin Formulations 3 and 4. Thepercent transparency decreased only slightly in Formulations 1 and 2 ascompared to the levels of transparency to PC-polysiloxane alone(Formulations 3 and 4). Formulation 1 with 85% PC-polysiloxane showed an82.4% transparency in comparisons to 85.5% transparency to Formulation 3with the same percentage of PC-polysiloxane. The percent haze using ASTMD 1003-7 at 0.125 inches in part thickness also showed a similar numberswhen comparing Formulation 1 with Formulation 3.

The impact performance test using ASTM D 256-10 (Notched IzodMeasurements) was conducted at four different temperatures for each ofthe Formulations (i.e., −10° C., −20° C., −30° C., and −40° C.). TheIzod test at low temperatures was used to differentiate amongst theFormulations by comparing the temperatures at which the Formulationsundergo a ductile/brittle transition. At −20° C., Formulation 1 (85%PC-polysiloxane/15% XHT) provided similar impact strength (J/M)ductility at −20° C. as Formulation 3 (85% PC-polysiloxane/15% PC-1).

Example 2 Additional Polycarbonate/Polysiloxane Compositions andCharacteristics Thereof

Various polycarbonate blends according to the Formulations specifiedbelow in Table 3 were tested for various attributes such as heatresistance, ductility, impact strength and transparency and the resultsare shown in Table 4.

TABLE 3 Formulation 1 2 3 4 5 6 7 8 9 10 PC-polysiloxane resin 85 85 8585 85 75 75 75 75 — PC-1 — — — —  5 — — — 8.3 67 PC-2 — — — — 10 — — —16.7 33 XHT Resin 15 — — — — 25 — — — — PPC Resin — — 15 — — — — 25 — —Bisphenol TMC resin — 15 — — — — 25 — — — Bisphenol AP resin — — — 15 —— — — — —

The PC-polysiloxane resin of Table 3 is a polycarbonate-siloxaneco-polymer, which has a molecular weight (Mw) of 23,000 and contains 6%siloxane. Such a resin may be made by the method described in U.S. Pat.No. 6,833,422, which is herein incorporated by reference in itsentirety.

The PC-1 resin of Table 3 is a 2,2-bis(4-hydroxyphenyl)propanepolycarbonate resin, which is cumyl phenol end capped. The PC-1 resinhas a molecular weight of 30,000.

The PC-2 resin of Table 3 is a 2,2-bis(4-hydroxyphenyl)propanepolycarbonate resin, which is cumyl phenol end capped. The PC-2 resinhas a molecular weight of 22,000.

The XHT resin of Table 3 is a polycarbonate consisting of 33 mole % of3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one and 67 mole %2,2-bis(4-hydroxyphenyl)propane. The XHT resin has a molecular weight(Mw) of 23,000 and a Tg of 198° C.

The PPC resin of Table 3 is a polyestercarbonate consisting of 26 mole %of 2,2-bis(4-hydroxyphenyl)propane polycarbonate, 69 mole % of2,2-bis(4-hydroxyphenyl)propane isophthalate polyester, and 5 mole %2,2-Bis(4-hydroxyphenyl)propane teraphthalate polyester. The PPC resinhas a molecular weight (Mw) of 28,500 and a Tg of 180° C.

The bisphenol TMC resin of Table 3 is a polycarbonate consisting of 33mole % of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 67mole % of 2,2-bis(4-hydroxyphenyl)propane. This bisphenol TMC resin hasa molecular weight (Mw) of 26,000 and a Tg of 182° C.

The bisphenol AP resin of Table 3 is a polycarbonate consisting of 75mole % of 1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane, and 25 mole % of2,2-bis(4-hydroxyphenyl)propane. The bisphenol AP resin has a molecularweight (Mw) of 22,600 and a Tg of 175° C.

TABLE 4 Formulation (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) GlassTransition Temp 152.5 148.3 148.7 148 145.5 153.6 151.2 151 144.5 148.4(Tg) MVR-360 cm3/10 min. 8.66 8.81 7.65 9.64 11.1 7.65 8.05 6.32 11.910.3 % haze std % 2.54 1.37 3.11 1.78 1.46 6.65 1.65 8.31 1.42 0.35 % Tstd % 82.8 85.5 81.4 84.5 85.8 76.5 84.7 74.5 85.7 89.7 Cnd:Temperature/1° C. −10 −10 −10 −10 −10 −10 −10 −10 −10 −10 Ductility/0%100 0 100 100 100 0 100 100 100 100 Impact Strength-Avg/0 J/M 605 689670 650 821 516 592 630 747 773 Cnd: Temperature/1° C. −20 −20 −20 −20−20 −20 −20 −20 −20 −20 Ductility/0% 80 100 100 100 100 0 0 100 100 0Impact Strength-Avg/0 J/M 581 645 660 607 726 480 558 619 736 425 Cnd:Temperature/1° C. −30 −30 −30 −30 −30 −30 −30 −30 −30 −30 Ductility/0% 0100 100 100 100 0 0 80 100 0 Impact Strength-Avg/0 J/M 556 607 620 611705 447 449 575 703 166 Cnd: Temperature/1° C. −40 −40 −40 −40 −40 −40−40 −40 −40 −40 Ductility/0% 0 0 0 0 80 0 0 0 40 0 Impact Strength-Avg/0J/M 487 570 622 574 685 351 214 559 674 135

All formulations were prepared by dry blending and extruded with aWerner Pfeidlere 30 mm twin screw at a temperature profile of 520° F. to550° F. The blended formulations were cut into pellets and injectionmolded at 540° F. to 580° F.

The glass transition temperature test indicated that each of the blendscontaining a polycarbonate or a polyestercarbonate with a Tg>170° C. hadsimilar glass transition temperatures ranging from 152.5° C. forFormulation 1 to 148° C. for Formulation 9. The melt volume flow ratetest (MVR) was conducted using ASTM D 1238-10 at 1.2 kg at 300° C. MVRdata indicates that with the exception of Formulation 3 (85%PC-polysiloxane/15% PPC), the various formulations met the targetedstandard of 6-12 or 8-12 for MVR.

Formulations 1-4 provided similar percent haze and transparencypercentages as the non-heat resistant PC-polysiloxane/PC-1/PC-2Formulation 5. Also, Formulations 1-4 provided similar impact strengthnumbers as Formulation 5. Formulation 1 provided 80% ductility at −20°C. while Formulations 2-4 provided 100% ductility at −20° C. and −30° C.Again, these formulations performed similar to the impact strength andductility of Formulation 5 and better than Formulation 10.

Overall, similar trends were seen in formulations 6-10.

1. A polycarbonate blend composition comprising: (a) a firstpolycarbonate having a glass transition temperature of greater than 170°C. as measured using a differential scanning calorimetry method, whereinthe first polycarbonate is derived from: (i) one or more monomers havingthe structure HO-A₁-Y₁-A₂-OH wherein each of A₁ and A₂ comprise amonocyclic divalent arylene group, and Y₁ is a bridging group having oneor more atoms, and wherein the structure is free of halogen atoms; or(ii) polyester monomer units having the structure

wherein D comprises one or more alkyl containing C₆-C₂₀ aromaticgroup(s), or one or more C₆-C₂₀ aromatic group(s), and T comprises aC₆-C₂₀ aromatic group; and (b) a second polycarbonate wherein the secondpolycarbonate is a polysiloxane block copolymer derived from (i) thestructure

wherein R comprises a C₁-C₃₀ aliphatic, a C₁-C₃₀ aromatic group, or acombination thereof, wherein Ar comprises one or more C₆-C₃₀ aromaticgroup(s), or one or more alkyl containing C₆-C₃₀ aromatic group(s),wherein E has an average value of 20-75; or (ii) the structure

wherein R comprises a C₁-C₃₀ aliphatic, a C₁-C₃₀ aromatic group, or acombination thereof, wherein R₆ comprise C₇-C₃₀ aromatic group, or acombination of a C₇-C₃₀ aromatic group and a C₇-C₃₀ aliphatic group,wherein E has an average value of 20-75; wherein the blend compositionhas a glass transition temperature (Tg) between 148° C. and 155° C. asmeasured using a differential scanning calorimetry method; wherein theblend composition has a percent (%) haze of less than 3.5% and a %transmission of greater than 80% as measured using a method of ASTM D1003-07; wherein the blend composition possesses 80% or greaterductility in a notched izod test at −20 C at a thickness of 0.125 inchesaccording to ASTM D 256-10.
 2. The blend composition of claim 1, whereinthe composition has an MVR of between 6 and 12 cm³/10 minute as measuredat 300° C. at 1.2 kilograms using the method of ASTM D 1238-10.
 3. Theblend composition of claim 1, wherein the second polycarbonate furthercomprises a carbonate unit derived from the polysiloxane blocks havingthe structure

wherein E has an average value of between 20 and
 75. 4. The blendcomposition of claim 1, wherein the first polycarbonate comprisescarbonate units derived from at least one of the following monomers3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP),1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane(Bisphenol-AP), and1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (Bisphenol-TMC). 5.The blend composition of claim 4, wherein the first polycarbonatecomprises greater than 30 wt % of carbonate units derived from at leastone of the following 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one(PPPBP), 1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane(Bisphenol-AP), and1,1-bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (Bisphenol-TMC). 6.The blend composition of claim 5, wherein the first polycarbonate has a% haze of less than 1.5% as measured using the method of ASTM D 1003-07at 0.125 inches in part thickness.
 7. The blend composition of claim 4,wherein the first polycarbonate further comprises carbonate unitsderived from 2,2-bis(4-hydroxyphenyl)propane (Bisphenol-A).
 8. The blendcomposition of claim 5, wherein the first polycarbonate furthercomprises carbonate units derived from 2,2-bis(4-hydroxyphenyl)propane(Bisphenol-A).
 9. The blend composition of claim 1, wherein firstpolycarbonate comprises aromatic ester units derived from isophthalicacid or terephthalic acids or isophthalic acid esters or terephthalicesters or a combination isophthalic acid or terephthalic acids orisopthalic acid esters or terephthalic acid esters.
 10. The blendcomposition of claim 9, wherein the first polycarbonate furthercomprises carbonate units or ester units derived from Bisphenol-A. 11.The blend composition of claim 1, wherein the second polycarbonate has ahaze of less than 3% as measured using the method of ASTM D 1003-07 at0.125 inches in part thickness and having 100% ductility at −20° C. asmeasured using the method of ASTM D 256-10 at 0.125 inches in partthickness.
 12. The blend composition of claim 1, wherein the first andsecond polycarbonates are made from either an interfacial polymerizationprocess and/or a melt polymerization process.
 13. The blend compositionof claim 1, wherein the wt % siloxane in the second polycarbonate isbetween 5 wt % and 7 wt % based on the total weight of the secondpolycarbonate.
 14. The blend composition of claim 1, wherein the wt % ofthe siloxane in the blend composition is between 4 wt % and 6 wt % basedon the total weight of the polycarbonate blend composition.
 15. Theblend composition of claim 1, wherein the second polycarbonate comprisesgreater than 75 wt % of the polycarbonate blend composition and whereinthe first polycarbonate comprises less than 25 wt % of the polycarbonateblend composition based on the sum of the first and secondpolycarbonates being equal to 100 wt %.
 16. The blend composition ofclaim 1, wherein the first polycarbonate comprises4,4′-(3,3,5-trimethylcyclohexane-1,1-diyl)diphenol.
 17. A polycarbonateblend composition comprising: (a) a first polycarbonate, which is acopolycarbonate having a glass transition temperature of 170° C. orgreater as measured using differential scanning calorimetry and derivedfrom a combination of bisphenol-A and a second monomer that is free ofhalogens and having the structure HO-A₁-Y₁-A₂-OH wherein each of A₁ andA₂ comprises a monocyclic divalent arylene group, and Y1 comprises atleast one of the following: —O—, —S—, —S(O)—, —S(O)₂—, methylene,cyclohexyl-methylene, 2-[2.2.1]-bicycloheptylidene, ethylidene,isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene,cyclododecylidene, and adamantylidene, wherein A₁, A₂ and Y₁ are free ofhalogen atoms; and (b) a second polycarbonate, which is a polysiloxaneblock copolycarbonate derived from at least bisphenol-A and

wherein the average value of E is between 30 and 50, or

wherein the average value of E is between 30 and 50, wherein thesiloxane content in the polysiloxane block co-polycarbonate is between 2wt % and 10 wt % siloxane based on the total weight of the polysiloxaneblock co-polycarbonate wherein the polycarbonate blend compositioncomprises between 10% and 20% of the first polycarbonate and between 90wt % and 80 wt % of the second polycarbonate based on the sum of thefirst and the second polycarbonate being equal to 100 wt % wherein thepolycarbonate blend composition has a glass transition temperature (Tg)of between 148° C. and 155° C. as measured using a differential scanningcalorimetry method, wherein the polycarbonate blend composition has a %haze of less than 3% and a % transmission of greater than 80% asmeasured using the method of ASTM D 1003-07; and, wherein thepolycarbonate blend composition possesses at least 75% ductility in anotched izod test at −20° C. at a thickness of 0.125 inches according toASTM D 256-10.
 18. The blend composition of claim 17, wherein the firstpolycarbonate is derived from at least Bisphenol-A and one or more ofthe monomers, 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one (PPPBP),Bisphenol-AP, Bisphenol-TMC or a combination of isophthalic and phthalicacids or a combination of isophthalic and phthalic acid esters.
 19. Theblend composition of claim 18, further comprising at least one of thefollowing additives: mold release agents, thermal stabilizers, UVstabilizers, or colorants.
 20. A polycarbonate blend compositioncomprising: (a) a first polycarbonate comprising carbonate units derivedfrom bisphenol-A and 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin-1-one(PPPBP), wherein the first polycarbonate has a mole % of carbonate unitsderived from PPPBP between 30-35 mole % and a mole % carbonate unitsderived from Bisphenol-A between 65 and 70 mole %, and (b) a secondpolycarbonate comprising carbonate units derived from Bisphenol-A andcarbonate units derived from

wherein, E has an average value of between 40 and 50 and wherein the wt% siloxane in the second polycarbonate is between 5 wt % and 7 wt %based on the weight of the second polycarbonate being 100%; wherein, thefirst polycarbonate comprises between 10-20 wt % and the secondpolycarbonate comprises between 80-90 wt % based on the wt % of thefirst and the second polycarbonate being 100%; wherein, thepolycarbonate blend composition comprises between 10% and 20% of thefirst polycarbonate and between 80 wt % and 90 wt % of the secondpolycarbonate based on the sum of the first and the second polycarbonatebeing equal to 100 wt %; wherein, the polycarbonate blend compositionhas a glass transition temperature (Tg) of between 148° C. and 155° C.as measured using a differential scanning calorimetry method; wherein, amolded article of the polycarbonate blend composition has a % haze ofless than 3% and a % transmission of greater than 80% as measured usingthe method of ASTM D 1003-07 at 0.125 inches in part thickness; whereinthe polycarbonate blend composition possesses at least 75% ductility ina notched izod test at −20° C. at a thickness of 0.125 inches accordingto ASTM D 256-10.
 21. A method for making the polycarbonate blendcomposition of claim 1 comprising the step of (a) selecting the firstpolycarbonate of claim 1; (b) selecting the second polycarbonate ofclaim 1; and (c) blending the first polycarbonate with the secondpolycarbonate to form a composition having a glass transitiontemperature (Tg) of between 145° C. and 155° C. as measured using adifferential scanning calorimetry method, a % haze of less than 3.5% anda % transmission of greater than as measured using the method of ASTM D1003-07; and, possesses 80% or greater ductility in a notched izod testat −20° C. at a thickness of 0.125 inches according to ASTM D 256-10.22. The method of claim 21, wherein (a) the first polycarbonatecomprises carbonate units derived from at least Bisphenol-A and one ormore of the following monomers (i) PPPBP; (ii) Bisphenol-A; (iii)Bisphenol-TCM; (iv) a combination of isophthalic and phthalic acids; and(v) a combination of isophthalic and phthalic acid esters; and (b) thesecond polycarbonate comprises carbonate units derived from Bisphenol-Aand

wherein the average value of E is between 30 and 50, or

wherein the average value of E is between 30 and
 50. 23. The method ofclaim 22, wherein step (c) comprises extrusion.
 24. An article moldedfrom the polycarbonate blend composition of claim
 1. 25. The article ofclaim 25, wherein the article is a component of a cell phone cover orcomputer housing.
 26. An article molded from the polycarbonate blendcomposition of claim 20.